Circuit breaker



Feb. 15 1938. F. KESSELRING CIRCUIT BREAKER Filed May 4, 1934 60/7170] Power Circuit Pressure 1 Fespazrswe Rainy M 2 I B I VENTOR F7772 K655627177;

ATTOR Y iatented Feb. 15,

UNITED STATES CIBCUIT BREAKER Fritz Kesaelring, Berlin- Hermsdori, Germany, as-

.signor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsylvania Application May 4, 1934, Serial No. 723,891

In Germany October 20, 1933 comma My invention relates'to circuit breakers of the type wherein a flowing stream or jet of gas or vapor is used for extinguishing the are which is established incident to the opening of the controlled circuit. Ordinarily, such breakers comprise a gas reservoir, an arc chamber and means for causing a flow of gas from the reservoir through the arc. The gas is usually discharged to the atmosphere, thus limiting the availability of gaseous substances for use with these breakers to those substances which are relatively inexpensive. The gas which is almost invariably used is air, and while reasonably satisfactory results have been secured with air-Jet breakers, their operation is not as satisfactory as might be desired.

One reason advanced for the unsatisfactory operation 0! these breakers has been the unsuitability of air-compared with certain other gaseous or vapor substances-as an arc extinguishing medium, and an extended investigation of the operational characteristics of this type circuit breaker indicates that this reason is the correct one. It appears from this investigation that two types of gases are particularly suitable for use in extinguishing electrical arcs. One type includes those gases which have good heat conductivity and high diiusion capacity. This group includes hydrogen, helium, and mercury vapor. The other type includes those inert and not readily ionizable gases such as arg'on, neon, crypton and xenon.

All of these gases, however, are relatively expensive, and ita circuit breaker wherein they are to be used is to be commercially practicable, some means must be provided whereby the gas or vapor can be used repeatedly for accomplishing are extinction.

This is the principal object of my invention, and the particular method which I prefer to utilize in accomplishing this object consists in the provision of a circuit breaker wherein the arc is established within a closed pressure system which includes means for causing a blast of gas 45 or vapor therethrough.

' More specifically, the circuit breaker of my inventionincludes a high pressure storage tank for the arc extinguishing gas, a low pressure tank, conducting means which includes an arc passage intermediate the two tanks, means for drawing the are within the arc passage, means for causing a flow of gas from the high pressure tank through the arc-passage to the'low pressure tank during the circuit opening operation, and a compressor or similar means for returning the gas to Cir the high pressure tank tollowing each circuit opening operation. By virtue of this arrange: ment the gas may be used repeatedly, and it is necessary that only a small quantity be provided for each individual breaker. The cost of the breaker is thus reduced to a minimum.

It is, of course, necessary that the chemical and physical properties of a gas or vapor suitable for use with a circuit breaker of this type shall not be permanently affected by being brought in contact with an electric are. All of the elemental gases mentioned above meet this requirement either when usedalone or in mixtures with each other.

It is of particular importance that all parts of the closed pressure system of the breaker shall be entirely gas-tight in order to prevent atmospheric dilution, and a particularly eflective means of preventing dilution consists in the maintaining of the pressure within the system at a value higher than the atmospheric pressure. If this is done, any small leakage will not affect the arc interrupting ability of the breaker. In order to indicate leaks in the pressure system, an odorant may be added to the gas or vapor, and, if desired, a refilling device may be associated with the pressure system for automatically replacing any gas which might be lost.

Referring to the drawing:

Figure 1 is an elevational view, partially in section, of a single-pole circuit breaker embodying the principal elements of my invention.

Fig. 2 is a front elevational view of the circuit breaker illustrated in Fig. 1.

' Fig. 3 is a sectional-view or a modified form of the circuit interrupter illustrated in Fig. 1.

Fig. 4 is an elevational view of the circuit interrupter shown in Fig. 3, and

' Fig. 5 is a schematic view of one form oi control circuit for the breaker shown in Figs. 1 and 2.

As shown in Figs. 1 and 2, the preferred form of my invention comprises a base i upon which are mounted a pair of hollow supporting insulators 3 and 5. The upper insulator 3 is adapted to support a high pressure tank I, and the lower insulator 5 is in turn adapted to support a low pressure tank 9. An insulating conduit H extends irom the high pressure tank I through the hollow upper insulator 3, the base I and the lower hollow insulator 5 to the low pressure tank 9, and is used for returning the gas to the high pressure tank f ollcwing the arc extinguishing operation.

An electro-magnetically operated valve i3 is positioned in the metallic conduit l5 leading from. the high pressure tank 1 toward thelo'w pres- 2. The piston 2| is of magnetic material and is adapted to be moved upwardly within the cylinder 23 by means oi a coil 25. The-piston 2| is moved to the open circuit position under the combined influence of gravity and the gas pressure existing within the closed pressure system during the cir cuit opening operation.

A tubular insulating member 2'! extends between the cylinder 22 and the conduit I! extending downwardly from the high pressure tank'l and serves to define the passage 2! wherein the arc is drawn and extinguished. The joints between the insulating member 21, the conduit l5, and the cylinder member 22 are all made gastight, as are the joints-between the two tanks and the conduit II in order that an entirely enclosed pressure system shall be provided.

The lower portion of the cylinder member 23 is provided with a pair oi opposed lateral openings 3| which open into the low pressure tank 9. When the breaker is in the closed circuit position the piston 2| moves so asto close the are w: e 2! from the low pressure tank. When the piston 2| moves to the open circuit position. however, these lateral openings II are uncovered, and the arc passage 22 is directly connected with the low pressure cylinder 8 in order that the gas blast initiated by the operation of the electro-magnetic valve It shall flow into the low pressure cylinder.

In order to return the gas which flows into the low pressure cylinder 9 during each are extinguishing operation, a compressor 83 is provided asshown in the drawing. This compressor is disposed entirely within the low pressure cylinder 0.

. The motor 3! which actuates this compressor is controlled by a valve 31 which is responsive to the diflerence in pressure existing between the high pressure and the low pressure tanks; the operation 01' the compressor is thus entirely automatic. This valve 21 also serves to normally close the conduit ll leadingiromthelowpressuretankto the highpressure tank, and since the electromagnetlc valve I3 is also normally closed, there is little possibility of leakage from the high Dressmetanktothelowpressuretankwhenthe breaker is standing idle for long periods in either the-open ortheclosedcircuit position.

Ordinarilythe pressurewithinallpartsoithe system is maintained somewhat above atmospheric in order that the gas within the closed pressuresystemshallnotbedilutedwith air. It desired,.a means such as the cylinder I! of compressed gas maybeprovlded for replacing'any Ieakage which mightoccur over long periods-oi Asmentionedabovqwhenthebreakeris intho closed circuit position. the arcing chamber 2| iswiththeupper terr minal 4|, which is rigidly aiilxed to the high pressure tank I, the current flows successively through the walls of the tanks I, the metallic conduit IS, the stationary contact it, the piston 2|, the cylinder 2!, and thence through the walls oi the low pressure tank 9 to the other terminal I! which is supported upon that tank. If desired a flexible shunt 45 may be provided for improving the electrical connection between the piston 2| and the cylinder member 23.

One form of control circuit for the breaker is shown schematically in Fig. 5. The circuit includes a three position switch 41, an overload relay it, and suitable conducting means for completing the electrical circuit to the various parts. The control circuit is so arranged that the breaker may be opened or closed through the actuation of the three position switch 41, provided that an overload capable of actuating the relay 49 does not exist in the power circuit. If such an overload does exist the breaker will automatically open regardless of the position of the switch 41. During the opening operation, the closing coil 25 is always deenergized and the electromagnetically operated valve It is always energized.

The circuit interrupter is shown in the closed circuit position in Fig. 1. In the device illustrated; it is intended that the cooperating portions of the contacts IT and II shall be held in engagement with each other by .the magnetic eiIect oi-the closing coil :L In this position, the movable blade it of the three position switch 41 engages the contact jaw II thereby completing the electrical circuit from one terminal of the control circuit to the contact point 58 of the relay 4!. The circuit through the relay is completed by the movable conducting means II which bridges the contact points It and I1, and

ing coil ll. The other side of the coil 2 is directly connectedto the other side of the control circuit.

To open the breaker manually, the switch ll is moved to complete the circuit to the second contact Jaw It. This movement causes the energization oi the electromagnetically operated valve I2, and simultaneously deenergiaes the closing coil 2!. The moving contact ll is then subjected to the combined forces of gravity and the pressure or the gas flowing through the hollow contact I! iron: the high pressure tank I, and, as a result, moves to the open circuit positionwithveryhigh velocity. Astreamoigas flowsthroughthehollow contact l1 andthe arc passage 2| and sheets a rapid extinguishment oi'the' are formed therein.

' Immediately following the are the point I1 is connected to one side of the closextinguishing operation the elc valve i3 automaticallrclosesthecondmtlllcading i'rom thehlgh pressuretank'ltothearcingchamberfl. This prevents waste of thegas and prolonged operationoithecompressor. Ittheinterrupteristo longedperiodthebladememberllismovedinto ent with the central law 03, thereby deenergisingullci'thebreakeructuatlngmeansexcepttheactuatingrelayi'liortheoompressor motor il morderthatasuflldentpressure s an-arm timesbemaintainedwithin thehigh pressuretanhtherelayflisneverdisconnected iromthecontrolpowercircuit.

Whentheintemipterisinthecloseddrcuit position and an overload oi suilicient magnitude toactuate the overloadrelayll occurs, thearremainintheopencircuitpositioniorauypromature ii or thatrelayliitsthe bridgingmem- 1| simultaneous energization of the electromagnetic valve II and a deenergization of the closing coil 25 whereupon the breaker opens exactly as described above for manual operation. Following the opening of the circuit, the armature 05 may be latched in an intermediate position, in order that the circuit through the contact points 53 and 51 and the circuit through points 61 and 60 shall be open. This will prevent the breaker from automatically reclosing if the switch 41 is not moved to the mid or normal open circuit position. If desired, a mechanical interlock may be provided for automatically moving the switch 41 to the neutral position when the breaker opens.

To close the circuit through the interrupter following an opening operation (either automatic or in response to movement of the switch 41) the switch blade 50 is moved to the closed position. The closing coil 25 is thereby energized and the magnetic piston-2i moves the contact rod into engagement with the fixed contact. Immediately following the arc extinction operation, the electro-magnetic valve I! automatically closes the conduit I5 leading from the high pressure tank 1 to the arcing chamber 20, and since the piston 2| substantially seals the cylinder 23 wherein it moves, the upward movement of the contact during the circuit closing operation is cushioned by virtue of the 'gas which is entrapped within the arc passage 29. This prevents damage to the engaging contact surfaces.

When the circuit interrupter is carrying a small load and the circuit opening operation is initiated, it often happens that the arc established incident to the separation of the contacts is extinguished before the lateral openings ll to the low pressure cylinder tare uncovered by the downwardly moving piston 2|. If this happens, the electromagnetic valve I! immediately closes the conduit I5 between the high pressure tank I and the arcing chamber 20 and thereby reduces to a minimum the amount of high pressure gas which is used during the opening of the circuit. This arrangement limits the power used by the compressor .30 and is of 'm'eat value in securing reliable operation of the device.

The modification illustrated in Figs. (land 4- is essentially similar to the device shown in Figs. 1 and 2'. It includes a low pressure tank II, a high pressure tank II, a conduit I5 leading from the high pressure tank to the low pressure tank, a compressor 'II adapted to cooperate with the conduit I! to return the gas which flows into the low pressure cylinder during the arc extinguishing operation to the high pressure cylinder, a pair of hollow insulators I and CI, an arcing chamber 03 the walls of which are of insulating material, and suitable conduit means intermediate the arcing chamber and the hollow insulator.

The hollow insulators themselves form a part of the closed pressure system in I'JS embodiment. It will be noted that the high pressure cylinder I3 is positioned entirely within the low pressurecylinder II, and that the compressor I1 and the actuating motor therefor are mounted within a suitable air-dome 01 supported upon the low pressure tank II. This arrangement is of considerable value in facilitating the servicing of the apparatus and in preventing the loss of any gas which might lead from the high pressure tank.

' low insulator 0| and the high pressure tank 13.

A metallic conduit means 83 is disposed intermediate the left-hand hollow insulator 8| and the arc passage 80 and is provided-with a cylinder portion 95 wherein the piston member 91 of. I magnetic material is-adapted to move. The left 1 hand terminal 90 is afllxed to this magnetic conduit means. i

The other metallic conduit means ,l0l which is disposed intermediate the right-hand hollow in- I sulator I9 and the arcing chamber 83 is provided with a tubular, stationary contact I03 similanto the contact H of the breaker shown .in Figs. 1c and 2. In addition, this condui t,;.i0i-is provided. with a plurality of suitably proportioned fins l.05

for radiating heat therefrom. A plurality of metallic cooling members II" are disposed within the conduit IM and the body portion of the insulator I8. The fins I05 and the metallic cooling members II" are positioned immediately subsequent, with respect to the path of flow of the arc extinguishing gas, to the arc passage and'are of service in preyenting undue heating of the gas which flows into-the low pressure tank II, during the operation of the interrupter, and thus assure that the back pressure existing therein will not be excessively large. I

The moving contact I09 is similar in design to the moving contact I9 of the device shown. in Figs. 1 and 2. Two operating coils III and 3 are provided for moving the piston 91 to open and to close the circuit.

The other terminal H5 of the interrupter is afllxed to the metallic conduit IOI thus producing a very simple and very direct current path through the interrupter. The shunt I I1 serves to electrically connect the plunger with the movable contact and piston assemblage.

The control circuit for the interrupter shown in Figs. 3 and 4 may be exactly similar to the circuit shown in Fig. 5, it being necessary merely to parallel the opening coil II3 with the electromagnetic valve.

The operation of the breaker illustrated in Figs. 3 and 4 is essentially similar to the operation of the breaker illustrated in Figs. 1 and 2. Upon the occurrence of an overload or other abnormal condition capable of actuating the control relay, or upon the manual operation of the control switch, the electro-magnetically operated valve 09 opens and causes a quantity of the gas entrapped within the high'pressure cylinder I3 to flow through the conduit 9| and the insulator II into the conduit 03 and the arc passage 83. The pressure of the gas aided by the energization of the opening coil I I3 moves the plunger 01 andwith it the moving contact I09 so as to establish an'arc within the arc passage. The gas flows through the arc passage and the hollow stationary contact I03 into the conduit IM and thence through the other hollow insulator I9 into the low pressure cylinder II. The out-flowing heated gas, as mentioned before, is cooled by means of the metallic cooling members I0'I disposed within the closed pressure system and the cooling fins I05.

The entire pressure system is, of course, gasti'ght and the operation of the motor 05 driving the compressor 11 is controlled by means of a valve H9 responsive to the'diflerence of pressure between the high pressure and the low pressure tanks.

It will thus be seen that I have disclosed a new improved circuit interrupter which utilizes a blast of a gas that is particularly effective in accomplishing the extinction of an electric arc and which is provided with a closed pressure system whereby the gas may be used repeatedly during .7 the life of the interrupter. This feature, whereby the same quantity of gas may be used a number of times is the principal feature of my invention. I have disclosed, however, certain preferred structural arrangements which are of particular value.

could be used. Numerous other arrangements likewise within the province of my invention will be apparent to one skilled in the art.

While in accordance with the patent statutes I have disclosed the foregoing details of certain preferred forms of my invention, it is to be understood that the principles disclosed are capabie of wide adaptation to the art of circuit interruption generally. It is my desire therefore that the language of the accompanying claims should be accorded the broadest reasonable construction and that my invention shall be limited only by what is expressly stated therein and by the prior art. a

I claim as my invention:

1. In a circuit interrupter; means for drawing an arc; a volume oiarc extinguishing gas; means for causing a quantity of said gas to flow through said are to en'ect its extinguishment; and means comprising a closed pressure system-tor permitting said quantity of gas to be used repeatedly without substantial loss; said closed pressure sys- .tem including a high Pressure tank wherein said 2. In a circuit interrupter; means for drawing' an arc; a volume of arc extinguishing gas; means for causing a quantity of said gas to flow through said are during each operation of said interrupter to eflect its extinguishment; and means comprising a closed pressure system for permitting said volume of gas to be used repeatedly without substantial loss; said closed prewure system including a high pressure tank wherein said gas is normally contained under high pressure, a low pressure tank into which said gas flows during each arc extinguishing operation, and a compressor for returning the gas which flows into the low pressure tank during the operation of the interrupter to the high pressure tank; said high pressure tank being disposed entirely within said low pressure tank, and being provided with valve means for preventing said gas from flowing to said low pressure tank except during the are extinguishing operation.

3. In a circuit interrupter; means defining a closed pressure system one portion of which comprises an arc passage; means for drawing an are within said are passage; means for introducing a quantity of a gas, into the arc passage portion of said closed system under suflicient pressure to cause a iiow oi gas through the arc; and means whereby said quantity 01 gas is used repeatedly, without substantial loss, during the operation of said interrupter; said closed pressure system including a metallic conduit portion positioned, with respect to the normal direction of flow of said gas, subsequent to the arc passage: said metallic'conduit portion being provided with externally disposed metallic cooling tins and internally disposed metallic cooling members. 

